Weaving looms employing moving warp-shed systems are known in the art, such as disclosed in U.S. Pat. No. 4,122,871. After the weft thread is inserted into the moving sheds formed by the warp threads, the weft thread must be moved or beat up to form the fabric at one end of the loom. Such mechanisms for beating up the weft thread are also known in the prior art. For example, a number of different beat-up arrangements are disclosed in U.S. Pat. No. 4,122,871. In one embodiment, the beat-up mechanism forms a part of the shed-retaining mechanism and is carried by a conveyor toward the fell of the fabric. The beat-up mechanism advances the weft thread toward the fell of the fabric and operates to beat up the weft thread into the fell of the fabric and is then withdrawn from the warp threads to be returned along the lower run of the conveyor to repeat another cycle. In such an arrangement, the number of beat-up elements extending transversely across the loom is very large, as these elements must be closely spaced in order to retain the sheds and beat up the weft thread. However, because of the large number of beat-up elements, as they are moved in the direction of the warp threads toward the fell of the fabric, friction is produced between the beat-up elements and the warp threads.
In another embodiment of U.S. Pat. No. 4,122,871, the conveyor carries a plurality of weft-advancing arms which advance the inserted weft thread toward the end of the conveyor adjacent the fell of the fabric. At that point, the weft-advancing arms push the weft thread into rotating reed members, and the weft-advancing arms are withdrawn from their position between the warp threads and are returned along the lower run of the conveyor to repeat another cycle. As the reed members rotate, they beat up the weft thread into the fell of the fabric. Although this arrangement is generally satisfactory, the rotating reed members continuously rotate against the warp threads at the fell of the fabric and thereby cause undesired friction on the warp threads.
In addition, when the above-described beat-up members or weft-advancing arms are withdrawn from between the warp threads and are returned along the lower run of the conveyor to the upper run of the conveyor, the weft-advancing arms or beat-up members must be reinserted in the spacing between the warp threads. However, the warp threads are relatively closely spaced, and no apparatus is provided to ensure that the weft-advancing arms or beat-up members are always properly reinserted into the warp threads to maintain the desired spacing between the warp threads.
Accordingly, it is an object of the present invention to provide an improved method and apparatus which overcomes the aforesaid problems. Specifically, it is within the contemplation of the present invention to provide an improved beat-up system which substantially reduces the friction on the warp threads and operates to continuously maintain the desired spacing between the warp threads while the weft threads are beat up into the fell of the fabric.
It is also an object of the present invention to provide a two-part mechanism for beating up the weft threads while continuously maintaining the spacing of the warp threads, so that at least one part of the two-part beat-up mechanism is always inserted in position between the warp threads to maintain their proper spacing.
It is a further object of the present invention to provide an arrangement for increasing the spacing between certain adjacent warp threads in the same plane so that the elements for retaining sheds, for beat up, or for weft advance may be more easily inserted between the specific warp threads desired, as such elements are returned to the upper run of the loom conveyor.